The invention relates to an open end rotor spinning machine with plural workstations each having a spinning device for producing a yarn, a yarn take-off mechanism and a winding device for producing a cross-wound bobbin rotatably held in a creel. More particularly, the spinning device has a spinning rotor circulating in a spinning housing at a high speed, a fiber band opening roller and a fiber band draw-in cylinder driven by a single drive, and the yarn take-off mechanism is loadable by a single drive.
Open end rotor spinning machines of this type, as known and described, for example, in German Patent Publication DE 198 36 065 A1, have a plurality of similar workstations arranged next to one another in a row, on which a fiber band preferably presented in a spinning can is spun to form a yarn and then wound to form a cross-wound bobbin. The individual workstations, in each case, for this purpose have a spinning device and a winding device, both the working members of the spinning device and the working members of the winding device generally being loaded via drive means along the length of the machine. In other words, arranged in the region of the spinning devices, are tangential belts to drive the spinning rotors and the fiber band opening rollers as well as a drive shaft along the length of the machine for loading the fiber band draw-in cylinder. The drive of the bobbin drive roller arranged in the region of the winding devices is also implemented via a drive shaft along the length of the machine. A yarn guide rod going back and forth is also present, which is loaded by a traversing gearing arranged at the end of the machine, and on which the yarn guides are fixed.
Furthermore, yarn take-off mechanisms are present, the driven take-off rollers of which are a component of a continuous drive shaft.
The workstations of such open end rotor spinning machines are attended to by service units, which patrol and automatically intervene, for example, along the workstations when a failure, for example, a yarn break, has occurred at one of the workstations. In such a case, the service unit runs to the relevant workstation, is locked thereat and with a pivotably mounted suction nozzle, which can be vacuum-loaded, seeks the yarn which has run onto the cross-wound bobbin after a yarn break. Apart from the suction nozzle, such service units also have a series of further yarn handling elements, which allow the yarn taken up by the suction nozzle, after a corresponding preparation in the open end rotor spinning device of the relevant workstation, to be repieced on a fiber ring circulating there with the spinning rotor. The individual yarn handling elements of the service unit, including the suction nozzle, are preferably driven by an electric motor which drives a cam disc pack which is connected via special lever rods to the yarn handling elements.
Service units of this type, which are described in relative detail, for example in German Patent Publication DE 198 27 605 A1, are relatively complicated, however, with respect to their design structure and therefore relatively cost-intensive.
Rotor spinning machines, which were still driven without such moveable service units, are also known from the past from German Patent Publications DE-OS 22 03 198 or DE-OS 25 34 816.
In the region of the yarn take-off tubes of their spinning devices, these open end rotor spinning machines, in each case, have a piecing aid, which makes it possible to shorten a yarn retrieved from a cross-wound bobbin to a specific length, to prepare it, convey it back to the rotor groove of a spinning rotor rotating in a spinning housing which can be loaded with a vacuum and to piece it there on a circulating fiber ring.
However, it is disadvantageous in these mechanisms that piecing a new yarn on the fiber ring circulating in the rotor groove takes place in a substantially uncontrolled manner. In other words, in these known mechanisms, there is neither an exact matching of the yarn feed into the spinning rotor nor an exact time matching of the yarn take-off to the speed of the spinning rotor and this leads to the fact that the yarn splices or piecings generated with these known mechanisms do not at all correspond to current quality standards.
Furthermore, open end rotor spinning devices are known which have various single drives in the region of their workstations.
Open end rotor spinning devices are described, for example in German Patent Publication DE 43 09 947 A1, in which the fiber band draw-in cylinder and/or the fiber band opening roller are driven, in each case, via a single drive.
An open end spinning machine is also known from German Patent Publication DE 100 62 096 A1, in which various single drives are arranged, in each case, in the region of the workstations. The workstations of this rotor spinning machine, for example, have an open end rotor spinning device with a single motor-driven fiber band draw-in cylinder, a single motor-driven yarn take-off mechanism and a single drive for the bobbin drive roller.
Furthermore, an open end rotor spinning machine, the workstations of which are configured such that they can automatically eliminate failures, in particular yarn breaks, is described in European Patent Publication EP 1 283 288 A2. The very substantially self-sufficient workstations of this known open end rotor spinning machine, apart from the spinning station's own suction nozzle, also inter alia have single drives for the bobbin drive roller and the yam take-off mechanism. The workstations also, in each case, have a piecing aid device which is arranged in the region of the open end rotor spinning device and in which the yarn provided by the suction nozzle is prepared for re-piecing.